An image forming apparatus includes a scanner motor and a rotary polygonal mirror which is driven by the scanner motor to rotate, and reflects a modulated beam emitted from a light source by a plurality of reflection surfaces. The image forming apparatus includes a rotation and carrier unit which, while rotating, carries an image formed on the basis of a laser beam reflected by the rotary polygonal mirror, a speed detection unit which detects a rotation speed of the rotation and carrier unit. The image forming apparatus includes a tracking characteristic detection unit which detects a tracking delay of the scanner motor from a target rotation speed and a control unit which controls, on the basis of the rotation speed detected by the speed detection unit and a tracking characteristic detected by the tracking characteristic detection unit, a rotation speed of the scanner motor that drives the rotary polygonal mirror.